A visa is a permit which is required to enter and remain in Sweden and the other Schengen states for a short period of time, e.g. to visit relatives or friends, as a tourist, on business, to attend a conference or simply to pass through (transit). A person who wishes to reside in Sweden, to be reunited with relatives for example, must apply for and be granted a residence permit before entering the country.
The visa should be complete and be entered in the passport before entry into the Schengen area.
The right to enter the Schengen area is examined every time you pass the outer border of the area. At the border control everyone who enters the area must be able to show that they have money for their keep during their visit and for their return journey home and that they have medical travel insurance and documents showing the purpose of their visit.